1. Field of the Invention
The invention relates to a thruster, more particularly to an underwater thruster.
2. Description of the Related Art
The development of remotely operated vehicles (ROVs) and autonomous underwater vehicles (AUVs) have helped tremendously in marine exploration. Such vehicles are generally installed with miniaturized thrusters capable of high output torque, low noise generation, and overload protection.
A ROV disclosed in U.S. Patent Application No. US2002/0083880 includes an underwater thruster having a stator that is magnetically and rotatably coupled to a propeller of the ROV for driving rotation of the propeller. Through magnetically driving the propeller, the risk of overloading the thruster is reduced. However, the absence of a transmission reduction mechanism could lead to an insufficient output torque.
Underwater vehicles disclosed in U.S. Pat. Nos. 3,765,185 and 4,114,555 have thrusters cooperatively associated with reduction gear boxes of the underwater vehicles. Although such an arrangement may provide a high output torque, since the reduction gearboxes are physically coupled to the thrusters, the thrusters may overload when foreign objects are caught in the thrusters.